Heat oven to 180°C (170°C for dark or nonstick pans). Make, bake and cool cake as directed on box for two 20cm or 23cm round cake pans.
In medium bowl, tint 1 container frosting with neon purple food color. Using 1 cake round, cut in half to form 2 semicircles. Put halves together with 60 grams frosting to form body. Place upright on serving plate, cut side down.
Frost cake with frosting. Cut ears from colored paper; wrap ends that will be inserted into cake with plastic food wrap. Insert into cake. Using toothpicks to attach, use 2 small marshmallow halves and 2 small jelly bean halves for eyes. Use large jelly bean for nose and sour candy strips for whiskers. Place gum halves just below nose for teeth. Use large marshmallow for tail.
Repeat with remaining cake to make second bunny, using pink food color. Frost and decorate as above. Remove ears, plastic wrap and toothpicks before serving. Store loosely covered.